1. Field of the Invention
The present invention relates to a power controller for executing internal power-on/power-off in response to a power control command received from another device in an audio/video device connected via a digital network according to IEEE 1394 or the like.
2. Discussion of the Related Art
In most cases of conventional televisions (hereinafter, referred to as “TV”) or the like, a power operation is performed from the outside of a TV main body; that is, power-on of a TV main body is performed by using a remote controller. The TV main body is powered on when a power-on command is received via a remote control signal in a standby state. Power-on is performed apparently in the presence of a user in the vicinity of the TV.
For the IEEE 1394 network, control commands of audio/video devices are standardized by an industrial standardization association. Mounting of a device-control-command processing program according to the standards enables the operation of audio/video devices including a TV, DVD player and VTR via a network. Power control commands (instructions) are prescribed in the standards. Using the commands enables the power-on/power-off of the device to be performed from an external device connected to the network. In addition, the power source of the audio/video device can be controlled from a personal computer in which software for transmitting the power control commands is installed.
In a VTR in which a video record reservation is set, on reaching reserved time, a primary power source is turned on from a standby state, and the power source state of a TV is checked. As a result of the checking, if the power source is in an off state, a power control command is issued to power on of the TV, and video recording is then started. In this case, if the video recording is reserved for a broadcast, a CRT of the TV need not be activated to illuminate; and it is preferable that only a tuner portion is powered on. However, when the VTR has transmitted a command to power on the overall device of the TV, a monitor portion including the CRT and a video output circuit is unexpectedly driven to operate. Driving the CRT to illuminate in the absence of the TV user is not preferable for the TV. This also produces disadvantages not only in safety but also in power saving.
Generally, while an audio/video device is configured of a plurality of functional blocks, functional blocks for performing power-on with a power control command are specified depending on controlled devices. As such, unnecessary power-on can take place for functional blocks which are unwanted to power on when, for example, a user is not in presence, and for either a TV display portion or monitor portion not viewed by a user.